# Thomas Aquinas' Five Ways Saint Thomas Aquinas, doctor of the Catholic Church, developed these five logical arguments, or his "five ways," for the [[! g - god exists|existence of God]] in his *Summa Theologica*. Here are those arguments, in brief. 1. **First Way - Argument from Motion** - Every motion is caused by something else. - An infinite chain of causes for motion is not logically possible. - Therefore, there must be a First Mover, God, that initiated all motion. 2. **Second Way - Argument from Efficient Cause** - Everything in existence has a cause. - An infinite chain of causes is not logically possible. - Therefore, there must be a First Cause, God, that set everything in motion. 3. **Third Way - Argument from Contingency** - Everything in the world is contingent, meaning it could either exist or not exist. - If everything is contingent, there must have been a time when nothing existed. - Therefore, there must be a necessary being, God, that explains the existence of contingent things. 4. **Fourth Way - Argument from Gradation** - There are degrees of qualities (goodness, truth, nobility) in the world. - There must be a standard of maximum perfection for these qualities. - Therefore, there must be a maximum in these qualities, which is God. 5. **Fifth Way - Argument from Design** - Order, purpose, and design are observed in the world. - This order and design imply an intelligent designer. - Therefore, there must be an intelligent designer, God, who is the ultimate source of purpose and design in the universe.